Spitfire XIV vs Bf-109 K-4 vs La-7 vs Yak-3

[drgondog]

Originally Posted by Hunter368

I will get you Bill.......................HAHAHAHAHAHAHAHAHAHA (evil laugh again if your wondering)

Hunter - Marcel, what I meant to say 'at least two minds alike SOMEWHERE on the spectrum'.. but then you would have known I meant the 'brilliant side not the Dim.

I have seen Dim and you guys 'aren't'

[Soren]

Stick to the topic guys, please, the argument between me and Bill will be solved soon enough.

[Hunter368]

Originally Posted by Soren

Stick to the topic guys, please, the argument between me and Bill will be solved soon enough.

Glad you are confident of that, it has been going on for a long time now......why would it stop all of a sudden?

[Soren]

Like I said in the post just before Bill's last post, I have contacted Gene (Crumpp) who is the foremost expert on the Fw-190 and aerodynamics we have had on this forum. I hope to be hearing from him soon so this hot debate will be solved.

Now please let us stick to the topic from here'on instead of keep sidetracking it like Bill started out doing and has successfully achieved.

If Bill is a grown up has something to say to me he can say it in the Soren vs Bill thread made, and the same goes for me.

Now lets stick to the topic, agree ?

[Hunter368]

Sounds good to us all.

[Soren]

Ok got message from Gene (Crumpp) and here's what he had to say (I left my questions to him first);


My mail to Gene (Crumpp):

Hello Crumpp,

I (Or we) need your knowledge on something, you see recently I got into an argument with a member at another forum for saying this:

The Fw-190's wing achieved elliptical lift distribution during G's because of aeroelasticity negating the original 2 degree twist applied to the 190's wing. This is what caused the violent departure in turns when pulling G's as compared to when stalling at 1 G.

This I learned from reading your posts as-well as Lednicer's article, however now I am being told I have misunderstood you & Lednicer by Bill, who you seem to know already. Bill says :
"the Fw 190 and the Spitfire and the Mustang all start with somewhat of an elliptical lift distribution BEFORE the turn and have an 'elliptical like' (more for Spit/less for Fw 190 and Mustang) lift distribution in the turn"

I disagree with what Bill says.

Could you explain the matter for us all (On the WW2 a/c forum) in detail in a PM to me here, then I will forward it to the forum. (Or you could put it on your blog here so everybody can see it right away)

The thread is named Spitfire XIV vs Bf-109 K-4 vs La-7 vs Yak-3. And plz ignor Bill & I's mud throwing, it has gotten completely out of hand..

Gene's response:

Hi Soren,

I hope things are going well for you. I appreciate your vote of confidence.

I do know Bill. He is not only very knowledgeable but someone I consider a friend. It is very disappointing to hear that you two cannot get along discussing old airplanes.

I can certainly clarify what I meant however the two points do not seem to be related or at least I cannot see how they are related. The only thing in common is the term "elliptical lift distribution". Lednicer is referring to the cl/CL ratio which gives us a clue as to the wing efficiency. The analysis is made at 360Kts at 15,000 feet and is good for that condition. Wing efficiency will change with condition of flight and square wingtips can very easily be designed that equal elliptical wings. However they are designed to be that optimal for a specific condition of flight. For example at the Prmin point, L/Dmax, or Va would serve as a design point depending on what the performance the designer desired.

Since the Mustang and FW190 are designed to most efficient at one design point and the Spitfire has an elliptical wing which is efficient at all points, Lednicer's observation is correct in that the Spitfire probably has the most optimal of the three. Probably is used because the aerodynamic twist in the Spitfire wings in order to prevent the wing from stalling all at once reduces this efficiency. That too would be designed for an optimal point of performance.

Make Sense?

Originally Posted by Soren

The Fw-190's wing achieved elliptical lift distribution during G's because of aeroelasticity negating the original 2 degree twist applied to the 190's wing. This is what caused the violent departure in turns when pulling G's as compared to when stalling at 1 G.

This statement refers to the fact aeroelasticity removes the aerodynamic twist placing the airfoil sections at the same co-efficient of lift. The sections then reach CLmax all at the same time. When one side of our wing or the tips stall, the aircraft will drop a wing or if the stall is large enough, the aircraft will roll inverted. That is what Lednicer is saying. This was not a design feature. It is just an explanation for the differences in the FW190's stall behaviors.

Originally Posted by Bill

"the Fw 190 and the Spitfire and the Mustang all start with somewhat of an elliptical lift distribution BEFORE the turn and have an 'elliptical like' (more for Spit/less for Fw 190 and Mustang) lift distribution in the turn"

That is pretty much what the spanwise lift loading notes. It has nothing to do with the stall behaviors of the FW190 but is gaining insight as to the relative efficiency of the wing designs..

Does that help?

All the best,

Crumpp

I then sent him another mail, just incase I might have misunderstood anything he said, and here's his answer (With my questions):

Originally Posted by Soren

I see, so I was wrong when I said that Fw-190's wing achieved basically fully elliptical lift distribution in turns ?

No you are right. That is what causes the harsh stall. It is not a design feature however. It is just and explanation for the two different stall characteristics of the design.

Originally Posted by Soren

It was my understanding that the Spitfire's wing didn't achieve fully elliptical lift distribution because of the washout applied to the wing all the way out to the tips.

You are right on this too. The Spitfire does not achieve the full efficiency benefits of elliptical wing construction due to the washout. At the same time though it is probably the most efficient of the three. If we examine the aircraft at a design optimum point, you will find little to no difference.


So the debate is now settled I hope.

[Kruska]

My Mamma also told me that I was right. But the Mamma of the other boy told her boy that he was right. Anyway my Mamma told me that I was still right, and I told this the other boy, who then told me that his Mamma told him that I was not right but he was, which in turn was disputed by me after My Mamma reconfirmed me that not the other boy whose Mamma told him that he was right actually was wrong, however the Mamma of the other boy disagreed with my Mammas opinion about me and not her boy being right……..

Okay so if anybody on this forum wants to know who actually was correct please let me know in order to continue this story because I actually was told by another boy that his Mamma didn’t think that the other boys Mamma was right in thinking that my Mamma was……….

Regards
Kruska

[Soren]

That's pretty ridiculous Kruska..

[drgondog]

Originally Posted by Soren

Ok got message from Gene (Crumpp) and here's what he had to say (I left my questions to him first);


My mail to Gene (Crumpp):



Gene's response:

Hi Soren,

I hope things are going well for you. I appreciate your vote of confidence.

I do know Bill. He is not only very knowledgeable but someone I consider a friend. It is very disappointing to hear that you two cannot get along discussing old airplanes.

I can certainly clarify what I meant however the two points do not seem to be related or at least I cannot see how they are related. The only thing in common is the term "elliptical lift distribution". Lednicer is referring to the cl/CL ratio which gives us a clue as to the wing efficiency. The analysis is made at 360Kts at 15,000 feet and is good for that condition. Wing efficiency will change with condition of flight and square wingtips can very easily be designed that equal elliptical wings. However they are designed to be that optimal for a specific condition of flight. For example at the Prmin point, L/Dmax, or Va would serve as a design point depending on what the performance the designer desired.

Since the Mustang and FW190 are designed to most efficient at one design point and the Spitfire has an elliptical wing which is efficient at all points, Lednicer's observation is correct in that the Spitfire probably has the most optimal of the three. Probably is used because the aerodynamic twist in the Spitfire wings in order to prevent the wing from stalling all at once reduces this efficiency. That too would be designed for an optimal point of performance.

Make Sense?




This statement refers to the fact aeroelasticity removes the aerodynamic twist placing the airfoil sections at the same co-efficient of lift. The sections then reach CLmax all at the same time. When one side of our wing or the tips stall, the aircraft will drop a wing or if the stall is large enough, the aircraft will roll inverted. That is what Lednicer is saying. This was not a design feature. It is just an explanation for the differences in the FW190's stall behaviors.





That is pretty much what the spanwise lift loading notes. It has nothing to do with the stall behaviors of the FW190 but is gaining insight as to the relative efficiency of the wing designs..

Does that help?

All the best,

Crumpp

I then sent him another mail, just incase I might have misunderstood anything he said, and here's his answer (With my questions):



No you are right. That is what causes the harsh stall. It is not a design feature however. It is just and explanation for the two different stall characteristics of the design.




You are right on this too. The Spitfire does not achieve the full efficiency benefits of elliptical wing construction due to the washout. At the same time though it is probably the most efficient of the three. If we examine the aircraft at a design optimum point, you will find little to no difference.


So the debate is now settled I hope.

Please forward the email to me in it's entirety. And please both thank Gene for his compliment and ask Gene to read this thread and ask him to comment.

I won't contact him directly to ask him to settle this but I would be interested if he wishes to do so at some future time

Then go back to my Post 77 where I discussed varying tip ratios to approximately .4 to obtain eliptical wing like induced drag... and discussed the effect of twist.. and the effect to twist when lift loads change due to aeroelastic effects.

Then please get to point of the effect of torsion versus bending on shift of load distribution causing the violent stall.

Then please go back to the post where I said that all wings show 'elliptical like' lift distributions, but the Spit moreso that the Fw 190 (and the Mustang)

Then please reflect that torsion at the wing tip is what caused the the entire wing to stall nearly at once.

The implication, which I don't think you grasped, was that the wing torsion caused the outer 20 percent to actually 'go positive' from zero twist, thereby increasing that region's approach to CLmax.. as the inboard 80% which was twisted to approach CLmax.

Then contrast that to what Gene said in his email

Then contrast what I have said before about control reversals on a Spit due to the aileron loads causing torsion in the wing at the tip.

Then contrast it to what I have said about manuevering performance is impossible to precisely predict relative to Cl as an example because that changes depending on the aeroelastic effects on the wing (and fuselage in both turn and other loads on the fuse bt the elevator and rudder) cause the geometry and angles of attack locally relative to freestream V.. affecting where it is in the CL curves relative to CLmax

Then go back and read what you just quoted from Gene - and last read what you said to start this debate.

Soren blurts - "However in the case of the 190 you will note that the wing twist was applied to such a degree as to provide elliptical lift distribution under G's (which btw is the reason for the violent departure), it was purposely done so to achieve the maximum 'e' factor and therefore L/D ratio in turns. Now ofcourse you wont see that on Lednicer's comparison as his simulation was done under 1 G, something you seem unable to grasp."

Now show each statement you got from Gene to prove your statement

You win - right??

[Hunter368]

Real debate going on now, facts. I love it.


Getting very interesting guys. Nice posting Bill and Soren

[Soren]

The email IS posted in its entirety Bill, nothing was left out or altered in any way. And you can contact Gene yourself if you don't believe me.

And as you can see in my email to him I directed him to read this thread.

Now I'm not going to play all hotshot on you Bill, don't worry, like you said no one is perfect. However I hope that from now on you'll keep your snide remarks to yourself and stop insinuating I don't know what I'm talking about.

So just admit defeat so we can get on with our lives man!

Thank you.

[Hunter368]

Hmmmmmmmmm

Not saying your right or not Soren (b/c I don't know), but you might of went to far rubbing his nose in it, IF you are right.

Stick to facts, if your facts are right.....no nose rubbing is needed. Facts speak louder then any gloating does. Your post is about 25% too much, rest is valid.

[drgondog]

Originally Posted by Kruska

My Mamma also told me that I was right. But the Mamma of the other boy told her boy that he was right. Anyway my Mamma told me that I was still right, and I told this the other boy, who then told me that his Mamma told him that I was not right but he was, which in turn was disputed by me after My Mamma reconfirmed me that not the other boy whose Mamma told him that he was right actually was wrong, however the Mamma of the other boy disagreed with my Mammas opinion about me and not her boy being right……..

Okay so if anybody on this forum wants to know who actually was correct please let me know in order to continue this story because I actually was told by another boy that his Mamma didn’t think that the other boys Mamma was right in thinking that my Mamma was……….

Regards
Kruska

Lol - My Momma thinks your Momma is right -

[Kruska]

Originally Posted by drgondog

Lol - My Momma thinks your Momma is right -

Thats because I lied to my Mamma

Regards
Kruska

[parsifal]

guys, the debate bit is excellent, and facinating, the sniping is c*ap. Maybe if you work together, we might all learn something.

keep at it (the debate i mean)